1. Field of the Invention
This invention relates generally to a latch assembly and more particularly to a mechanism for selectively latching and accurately positioning relatively separable members.
2. Description of the Prior Art
The need for selective latching mechanisms for separable members has long been known. Mechanisms proposed to accomplish this end have been as simple hook-and-eye assemblies and as complex as intricate linkage arrangements with remote lever release controls. In general, however, the prior art latches have been concerned only with selectively retaining separable members together; holding a critical spacing between the latched members has not been of particular consideration. When clearance between the separable members has been desired, it is usually accomplished by stops provided directly on one of the particular members being latched.
There has recently been disclosed in U.S. patent application Ser. No. 647,683, filed Jan. 8, 1976 which is a continuation of Ser. No. 523,610 filed Nov. 13, 1976 and now abandoned in the name of M. J. Russel, a document feeding apparatus which feeds sheets across the glass platen of an electrophotographic copier. The relative spacing between feeding apparatus and the platen is critical to the proper feeding of the sheets across the platen; i.e., the spacing must be accurately controlled to enable the feeder to apply sufficient forces to the sheets to move the sheets across the platen, but not such forces as would damage the sheets. The feeding apparatus is pivotably movable to a position to overlie the glass platen but is biased toward a separated position to facilitate lifting thereof by an operator desiring access to the platen. Since, as noted, the platen is made of glass (and therefore subject to breakage), and further since there must be a clear path for sheet transport, it is not convenient to use conventional stops to provide the accurate location of the feeder relative to the platen.